From 970094f8c73d8ef2ebfc714918c17352fc288367 Mon Sep 17 00:00:00 2001
From: Gaurav Dhingra <gauravdhingra.gxyd@gmail.com>
Date: Tue, 25 Mar 2025 18:41:29 +0530
Subject: [PATCH 1/3] CI: run standalone tests with MPI rank 4 as well

---
 tests/run_tests.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index 5eaaabf..367df3e 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -26,7 +26,7 @@ for file in *.f90; do
   $FC -c $file
   $FC mpi_wrapper.o mpi_c_bindings.o mpi.o $filename.o -o $filename -L$CONDA_PREFIX/lib -lmpi -Wl,-rpath,$CONDA_PREFIX/lib
 
-  for np in 1 2; do
+  for np in 1 2 4; do
     echo -e "${YELLOW}Running $filename with $np MPI ranks...${NC}"
     if ${MPIEXEC} -np $np ./$filename; then
       echo -e "${GREEN}Test $filename with $np MPI ranks PASSED!${NC}"

From 029762cd6004267a2e8bcfd2bf0f418b68089055 Mon Sep 17 00:00:00 2001
From: Gaurav Dhingra <gauravdhingra.gxyd@gmail.com>
Date: Wed, 26 Mar 2025 09:23:23 +0530
Subject: [PATCH 2/3] use `--oversubscribe` option with Open MPI but not with
 MPICH

---
 tests/run_tests.sh | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index 367df3e..5a3b427 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -9,6 +9,21 @@ NC='\033[0m' # No Color
 
 MPIEXEC=${CONDA_PREFIX}/bin/mpiexec
 
+# Detect MPI implementation
+# NOTE: I've noticed that using '--oversubscribe' with Open MPI takes a
+# lot of time to run on local machine, than without it
+MPI_VERSION=$($MPIEXEC --version 2>&1)
+if echo "$MPI_VERSION" | grep -q "Open MPI"; then
+  MPI_TYPE="openmpi"
+  MPIEXEC_ARGS="--oversubscribe"
+elif echo "$MPI_VERSION" | grep -q "MPICH"; then
+  MPI_TYPE="mpich"
+  MPIEXEC_ARGS=""  # MPICH usually allows oversubscription by default
+else
+  echo -e "${RED}Unknown MPI implementation!${NC}"
+  exit 1
+fi
+
 if [[ "$(uname)" == "Linux" ]]; then
   CC=gcc
 else
@@ -28,7 +43,7 @@ for file in *.f90; do
 
   for np in 1 2 4; do
     echo -e "${YELLOW}Running $filename with $np MPI ranks...${NC}"
-    if ${MPIEXEC} -np $np ./$filename; then
+    if ${MPIEXEC} -np $np $MPIEXEC_ARGS ./$filename; then
       echo -e "${GREEN}Test $filename with $np MPI ranks PASSED!${NC}"
     else
       echo -e "${RED}Test $filename with $np MPI ranks FAILED!${NC}"

From 5da468d752d6abf6b48948f176ec5deea36643da Mon Sep 17 00:00:00 2001
From: Gaurav Dhingra <gauravdhingra.gxyd@gmail.com>
Date: Wed, 26 Mar 2025 09:39:20 +0530
Subject: [PATCH 3/3] don't use `--oversubscribe` for rank 1 or rank 2 with
 Open MPI

---
 tests/run_tests.sh | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index 5a3b427..4f510b0 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -9,17 +9,15 @@ NC='\033[0m' # No Color
 
 MPIEXEC=${CONDA_PREFIX}/bin/mpiexec
 
-# Detect MPI implementation
-# NOTE: I've noticed that using '--oversubscribe' with Open MPI takes a
-# lot of time to run on local machine, than without it
+# detect MPI implementation
 MPI_VERSION=$($MPIEXEC --version 2>&1)
 if echo "$MPI_VERSION" | grep -q "Open MPI"; then
   MPI_TYPE="openmpi"
-  MPIEXEC_ARGS="--oversubscribe"
 elif echo "$MPI_VERSION" | grep -q "MPICH"; then
   MPI_TYPE="mpich"
-  MPIEXEC_ARGS=""  # MPICH usually allows oversubscription by default
 else
+  # we don't yet support other MPI implementations
+  # like intel MPI etc.0
   echo -e "${RED}Unknown MPI implementation!${NC}"
   exit 1
 fi
@@ -30,7 +28,7 @@ else
   CC=clang
 fi
 
-# Compile C and Fortran sources
+# compile C and Fortran sources
 $CC -I$CONDA_PREFIX/include -c ../src/mpi_wrapper.c
 $FC -c ../src/mpi_c_bindings.f90
 $FC -c ../src/mpi.f90
@@ -42,6 +40,15 @@ for file in *.f90; do
   $FC mpi_wrapper.o mpi_c_bindings.o mpi.o $filename.o -o $filename -L$CONDA_PREFIX/lib -lmpi -Wl,-rpath,$CONDA_PREFIX/lib
 
   for np in 1 2 4; do
+    # set MPIEXEC_ARGS based on MPI type and number of ranks
+    # `--oversubscribe` isn't needed with Open MPI when running
+    # with 1 or 2 ranks
+    if [[ "$MPI_TYPE" == "openmpi" && $np -gt 2 ]]; then
+      MPIEXEC_ARGS="--oversubscribe"
+    else
+      MPIEXEC_ARGS=""
+    fi
+
     echo -e "${YELLOW}Running $filename with $np MPI ranks...${NC}"
     if ${MPIEXEC} -np $np $MPIEXEC_ARGS ./$filename; then
       echo -e "${GREEN}Test $filename with $np MPI ranks PASSED!${NC}"